This invention relates to serial sampling video signal driving apparatus for a matrix-type color display.
A matrix-type display comprises a matrix of discrete picture elements, herein called dots. In the case of a color display, each dot has means for displaying, for example, the three primary colors red, blue, and green. The serial sampling video signal driving circuit receives red, blue, and green input video signals, samples them in a serial manner, and provides video output signals to drive the display. "A serial manner" means that the three video signals are sampled one after the other instead of simultaneously.
One example of a matrix-type color display with a serial sampling video signal driving circuit is a color liquid crystal display for a computer. The computer produces red, green, and blue video signals synchronized to a dot clock.
Although-the video signals are analog and since they are produced by a computer, each signal tends to have a discrete value per dot, the value changing abruptly at boundaries between dots. A problem that occurs in tills situation is incorrect color rendition at high spatial frequencies because signal sampling is not synchronized to the dot clock. A vertical edge between a white area and a black area, for example, may be tinged with undesired colors. This problem is particularly noticeable if the serial sampling video signal driving apparatus and its constituent signal-processing circuits are not designed for extremely high-frequency operation. The problem can be alleviated by using circuits with improved high-frequency characteristics, but such circuits are expensive and dissipate additional power.